Imaging device and imaging system controlling the read out of signals from a plurality of pixels

ABSTRACT

An imaging device includes pixels each including a holding portion, and an output unit, and a control unit that controls readout of pixel signals. The pixels include first to fourth pixels that output signals based on light of first to fourth wavelength ranges. A first unit pixel includes the first and second pixels but no third pixel, which share the holding portion. A second unit pixel includes the first and third pixels but no second pixel, which share the holding portion. A third unit pixel includes the first and fourth pixels but neither second nor third pixel, which share the holding portion. The control unit reads, from the first unit pixel, a signal in which signals of the first and second pixels are added in the holding portion, and reads, from the third unit pixel, a signal in which signals of the first pixels are added in the holding portion.

BACKGROUND OF THE INVENTION Field of the Invention

The present disclosure relates to an imaging device and an imagingsystem.

Description of the Related Art

In a single-plate type imaging device, to obtain a color image, colorfilters (CF) which transmit lights of respective colors of particularwavelength components, for example, red (R), green (G), and blue (B) arearranged over pixels in a predetermined pattern. As a CF pattern, apattern with so-called Bayer arrangement is widely used. Further, inaddition to the CF of RGB, a use of a CF with RGBW arrangement having Wpixels that has filters which transmit light of a whole wavelength rangeof visible light has become prevalent.

Japanese Patent Application Laid-Open No. 2016-213715 and JapanesePatent Application Laid-Open No. 2015-088947 disclose an imaging devicehaving a CF with the RGBW arrangement. The imaging device having the CFwith the RGBW arrangement can improve sensitivity and acquire an imagewith a high S/N ratio by using W pixels.

As a scheme for improving sensitivity of an imaging device, a method ofadding (also referred to as binning) and reading out pixel signals of aplurality of pixels is known. One way to add pixel signals may be, in aplurality of pixels sharing a floating diffusion portion, to transfersignal charge generated in photoelectric converters of the plurality ofpixels to a single floating diffusion portion and read out thetransferred signal charge as a single pixel signal.

In the configuration of the imaging device disclosed in Japanese PatentApplication Laid-Open No. 2015-088947, however, since color pixels ofdifferent colors share a floating diffusion portion, color mixture mayoccur when pixel signals are added by using a floating diffusionportion, and color reproducibility may decrease.

SUMMARY OF THE INVENTION

The present disclosure intends to provide an imaging device and animaging system that can improve sensitivity without deteriorating colorreproducibility and acquire an image with a high S/N ratio.

According to one aspect of the present disclosure, provided is animaging device including a plurality of pixels each including aphotoelectric converter, a holding portion to which charge generated inthe photoelectric converter is transferred, and an output unit thatoutputs a signal in accordance with an amount of charge held in theholding portion, and a control unit that controls readout of signalsfrom the plurality of pixels. The plurality of pixels includes aplurality of first pixels each configured to output a signal inaccordance with a light of a first wavelength range, a plurality ofsecond pixels each configured to output a signal in accordance with alight of a second wavelength range that is different from the firstwavelength range, a plurality of third pixels each configured to outputa signal in accordance with a light of a third wavelength range that isdifferent from the first wavelength range and the second wavelengthrange, and a plurality of fourth pixels each configured to output asignal in accordance with a light of a fourth wavelength range that isdifferent from the first wavelength range, the second wavelength range,and the third wavelength range. The plurality of pixels forms aplurality of first unit pixels each including the first pixels and thesecond pixel but not including the third pixel, in which the firstpixels and the second pixel share the holding portion, a plurality ofsecond unit pixels each including the first pixels and the third pixelbut not including the second pixel, in which the first pixels and thethird pixel share the holding portion, a plurality of third unit pixelseach including the first pixels and the fourth pixel but not includingthe second pixel and the third pixel, in which the first pixels and thefourth pixel share the holding portion. The control unit reads out, fromeach of the plurality of first unit pixels, a signal in which signals ofthe first pixels and a signal of the second pixel are added in theholding portion, and the control unit is configured to read out, fromeach of a part of the plurality of third unit pixels, a signal in whichsignals of the first pixels are added in the holding portion bytransferring charges of the photoelectric converters of the first pixelsto the holding portion without transferring charge of the photoelectricconverter of the fourth pixel.

Further, according to another aspect of the present disclosure, providedis a signal processing device including a signal processing unit thatprocesses signals output from an imaging device including a plurality ofpixels including a first pixel having higher sensitivity than a secondto fourth pixels, the second pixel configured to output a signalincluding color information of a first color, the third pixel configuredto output a signal including color information of a second color that isdifferent from the first color, and the fourth pixel configured tooutput a signal including color information of a third color that isdifferent from the first color and the second color. The imaging deviceoutputs first addition data in which a signal of the second pixel and asignal of the first pixel are added, second addition data in which asignal of the third pixel and a signal of the first pixel are added, andthird addition data in which a signal of the fourth pixel and a signalof the first pixel are added, and the signal processing unit calculatescolor difference data between the first color and the third color bysubtracting the third addition data from the first addition data andcalculates color difference data between the second color and the thirdcolor by subtracting the third addition data from the second additiondata.

Further, according to another aspect of the present disclosure, providedis a signal processing device including a signal processing unit thatprocesses signals output from an imaging device including a plurality ofpixels including a first pixel having higher sensitivity than a secondto fourth pixels, the second pixel configured to output a signalincluding color information of a first color, the third pixel configuredto output a signal including color information of a second color that isdifferent from the first color, and the fourth pixel configured tooutput a signal including color information of a third color that isdifferent from the first color and the second color. The imaging deviceoutputs first addition data in which a signal of the second pixel and asignal of the first pixel are added, second addition data in which asignal of the third pixel and a signal of the first pixel are added,third addition data in which a signal of the fourth pixel and a signalof the first pixel are added, and fourth addition data in which signalsof the first pixel are added, and the signal processing unit calculatescolor data of the first color by subtracting the fourth addition datafrom the first addition data, calculates color data of the second colorby subtracting the fourth addition data from the second addition data,and calculates color data of the third color by subtracting the fourthaddition data from the third addition data.

Further features of the present disclosure will become apparent from thefollowing description of exemplary embodiments with reference to theattached drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram illustrating a general configuration of animaging device according to a first embodiment of the presentdisclosure.

FIG. 2 is a circuit diagram illustrating a configuration example of aunit pixel of the imaging device according to the first embodiment ofthe present disclosure.

FIG. 3 is a plan view illustrating a pixel block of a pixel region inthe imaging device according to the first embodiment of the presentdisclosure.

FIG. 4 is a plan view illustrating a configuration example of a unitpixel of the imaging device according to the first embodiment of thepresent disclosure.

FIG. 5 and FIG. 6 are flowcharts illustrating methods of driving theimaging device according to the first embodiment of the presentdisclosure.

FIG. 7 is a diagram illustrating data arrangement when pixel addition isperformed on a unit pixel basis in the method of driving the imagingdevice according to the first embodiment of the present disclosure.

FIG. 8 and FIG. 9 are diagrams illustrating color interpolation methodsin the method of driving the imaging device according to the firstembodiment of the present disclosure.

FIG. 10 is a flowchart illustrating a method of driving an imagingdevice according to a second embodiment of the present disclosure.

FIG. 11 is a diagram illustrating a color interpolation method in themethod of driving the imaging device according to the second embodimentof the present disclosure.

FIG. 12 is a plan view illustrating a unit block of a pixel region in animaging device according to a third embodiment of the presentdisclosure.

FIG. 13 is a circuit diagram illustrating a configuration example of aunit pixel of an imaging device according to a fourth embodiment of thepresent disclosure.

FIG. 14 and FIG. 15 are timing diagrams illustrating methods of drivingthe imaging device according to the fourth embodiment of the presentdisclosure.

FIG. 16 is a circuit diagram illustrating a configuration example of aunit pixel of an imaging device according to a fifth embodiment of thepresent disclosure.

FIG. 17 and FIG. 18 are timing diagrams illustrating methods of drivingthe imaging device according to the fifth embodiment of the presentdisclosure.

FIG. 19 is a block diagram illustrating a general configuration of animaging system according to a sixth embodiment of the presentdisclosure.

FIG. 20A is a diagram illustrating a configuration example of an imagingsystem according to a seventh embodiment of the present disclosure.

FIG. 20B is a diagram illustrating a configuration example of a movableobject according to the seventh embodiment of the present disclosure.

DESCRIPTION OF THE EMBODIMENTS First Embodiment

An imaging device and a method of driving the same according to a firstembodiment of the present disclosure will be described with reference toFIG. 1 to FIG. 9.

First, the structure of an imaging device according to the presentembodiment will be described with reference to FIG. 1 to FIG. 4. FIG. 1is a block diagram illustrating a general configuration of the imagingdevice according to the present embodiment. FIG. 2 is a circuit diagramillustrating a configuration example of a unit pixel of the imagingdevice according to the present embodiment. FIG. 3 is a plan viewillustrating a pixel block of a pixel region in the imaging deviceaccording to the present embodiment. FIG. 4 is a plan view illustratinga configuration example of a unit pixel of the imaging device accordingto the present embodiment.

As illustrated in FIG. 1, an imaging device 100 according to the presentembodiment includes a pixel region 10, a vertical scanning circuit 30, areadout circuit 40, a horizontal scanning circuit 50, an output circuit60, and a control circuit 70.

In the pixel region 10, a plurality of unit pixels 12 arranged in amatrix over a plurality of rows and a plurality of columns are provided.Each of the unit pixels 12 includes a photoelectric conversion elementthat converts an incident light into charge in accordance with the lightamount. The number of rows and the number of columns of the unit pixels12 arranged in the pixel region 10 are not particularly limited.Further, in the pixel region 10, in addition to the unit pixels 12 thatoutput signals in accordance with the light amount of an incident light,other pixels (not illustrated) such as an optical black pixel that isshielded from light, a dummy pixel that does not output a signal, or thelike may be arranged.

On each row of the pixel region 10, a control line 14 extending in afirst direction (the horizontal direction in FIG. 1) is provided. Thecontrol line 14 is connected to the unit pixels 12 aligned in the firstdirection, respectively, to form a signal line common to these unitpixels 12. The first direction in which the control line 14 extends maybe referred to as a row direction or the horizontal direction. Thecontrol line 14 on each row is connected to the vertical scanningcircuit 30. Note that the control line 14 on each row may include aplurality of signal lines.

On each column of the pixel region 10, an output line 16 extending in asecond direction (the vertical direction in FIG. 1) crossing the firstdirection is provided. The output line 16 is connected to the unitpixels 12 aligned in the second direction, respectively, to form asignal line common to these unit pixels 12. The second direction inwhich the output line 16 extends may be referred to as a columndirection or the vertical direction. The output line 16 on each columnis connected to the readout circuit 40. Note that the output line 14 oneach column may include a plurality of signal lines.

The vertical scanning circuit 30 is a control unit that supplies, to theunit pixels 12 via the control lines 14 provided on a row basis in apixel region 10, control signals used for driving readout circuitsinside the unit pixels 12 when reading out a signal from each of theunit pixels 12. The vertical scanning circuit 30 may be formed by usinga shift register or an address decoder. Signals read out from the unitpixels 12 are input to the readout circuit 40 via the output lines 16provided on a column basis in the pixel region 10.

The readout circuit 40 is a circuit unit that performs predeterminedprocessing, for example, signal processing such as an amplificationprocess, an addition process, or the like on a signal read out from theunit pixel 12. The readout circuit 40 may include a signal holdingportion, a column amplifier, a correlated double sampling (CDS) circuit,an addition circuit, or the like. The readout circuit 40 may furtherinclude an analog-to-digital (A/D) converter circuit or the like ifnecessary.

The horizontal scanning circuit 50 is a circuit unit that supplies, tothe readout circuit 40, control signals used for transferring signalsprocessed in the readout circuit 40 to the output circuit 60sequentially on a column basis. The horizontal scanning circuit 50 maybe formed by using a shift register or an address decoder. The outputcircuit 60 is a circuit unit formed of a buffer amplifier, adifferential amplifier, or the like and configured to amplify a signalon a column selected by the horizontal scanning circuit 50 and outputthe amplified signal.

The control circuit 70 is a circuit unit used for supplying, to thevertical scanning circuit 30, the readout circuit 40, and the horizontalscanning circuit 50, control signals that controls the operations or thetimings thereof. Some or all of the control signals supplied to thevertical scanning circuit 30, the readout circuit 40, and the horizontalscanning circuit 50 may be supplied from the outside of the imagingdevice 100.

As illustrated in FIG. 2, for example, each of the unit pixels 12 may beconfigured to include photoelectric converters PDA, PDB, PDC, and PDD,transfer transistors M1A, M1B, M1C, and M1D, a reset transistor M2, andan amplifier transistor M3. Note that, in the following description,when the photoelectric converters PDA, PDB, PDC, and PDD arecollectively illustrated, which may be denoted as the photoelectricconverter(s) PD. Further, when collectively illustrated, the transfertransistors M1A, M1B, M1C, and M1D may be denoted as the transfertransistor(s) M1.

Each of the photoelectric converters PDA, PDB, PDC, and PDD is aphotodiode, for example. The photodiode of the photoelectric converterPDA has the anode connected to a ground voltage node and the cathodeconnected to the source of the transfer transistor M1A. The photodiodeof the photoelectric converter PDB has the anode connected to a groundvoltage node and the cathode connected to the source of the transfertransistor M1B. The photodiode of the photoelectric converter PDC hasthe anode connected to a ground voltage node and the cathode connectedto the source of the transfer transistor M1C. The photodiode of thephotoelectric converter PDD has the anode connected to a ground voltagenode and the cathode connected to the source of the transfer transistorM1D.

The drains of the transfer transistors M1A, M1B, M1C, and M1D areconnected to the source of the reset transistor M2 and the gate of theamplifier transistor M3. The connection node of the drains of thetransfer transistors M1A, M1B, M1C, and M1D, the source of the resettransistor M2, and the gate of the amplifier transistor M3 is aso-called floating diffusion portion FD. The floating diffusion portionFD includes a capacitance component (floating diffusion capacitance) andforms a holding portion for charge caused by the capacitance component.

The drain of the reset transistor M2 and the drain of the amplifiertransistor M3 are connected to the power supply voltage node (voltageVdd). Note that the voltage supplied to the drain of the resettransistor M2 and the voltage supplied to the drain of the amplifiertransistor M3 may be the same or may be different from each other. Thesource of the amplifier transistor M3 is connected to the output line 16on a column associated with the unit pixel 12 of interest. A currentsource 18 is connected to the output line 16.

The readout circuit 40 is connected to the output line 16 as describedabove. FIG. 2 illustrates, as a part of components of the readoutcircuit 40, a switch SW1 and a column amplifier 42 connected to theoutput line 16 on a column associated with the unit pixel 12 ofinterest.

In the case of the unit pixel 12 having the configuration illustrated inFIG. 2, the control line 14 arranged on each row of the pixel region 10may include five signal lines that supply control signals PTXA, PTXB,PTXC, PTXD, and PRES. The signal line that supplies the control signalPTXA is connected to the gates of the transfer transistors M1A on theunit pixels 12 belonging to the corresponding row, respectively, to forma signal line common to these unit pixels 12. The signal line thatsupplies the control signal PTXB is connected to the gates of thetransfer transistors M1B on the unit pixels 12 belonging to thecorresponding row, respectively, to form a signal line common to theseunit pixels 12. The signal line that supplies the control signal PTXC isconnected to the gates of the transfer transistors M1C on the unitpixels 12 belonging to the corresponding row, respectively, to form asignal line common to these unit pixels 12. The signal line thatsupplies the control signal PTXD is connected to the gates of thetransfer transistors M1D on the unit pixels 12 belonging to thecorresponding row, respectively, to form a signal line common to theseunit pixels 12. The signal line that supplies the control signal PRES isconnected to the gates of the reset transistors M2 on the unit pixels 12belonging to the corresponding row, respectively, to form a signal linecommon to these unit pixels 12.

When each transistor forming the unit pixel 12 is formed of an n-channeltransistor, when a high-level control signal is supplied from thevertical scanning circuit 30, a corresponding transistor is turned on.Further, when a low-level control signal is supplied from the verticalscanning circuit 30, a corresponding transistor is turned off.

Each of the photoelectric converters PDA, PDB, PDC, and PDD converts(photoelectrically converts) an incident light into an amount of chargein accordance with the light amount and accumulates the generatedcharge. The transfer transistor M1A is controlled by the control signalPTXA and, when turned on, transfers charge held by the photoelectricconverter PDA to the floating diffusion portion FD. Similarly, thetransfer transistor M1B is controlled by the control signal PTXB and,when turned on, transfers charge held by the photoelectric converter PDBto the floating diffusion portion FD. Further, the transfer transistorM1C is controlled by the control signal PTXC and, when turned on,transfers charge held by the photoelectric converter PDC to the floatingdiffusion portion FD. Further, the transfer transistor M1D is controlledby the control signal PTXD and, when turned on, transfers charge held bythe photoelectric converter PDD to the floating diffusion portion FD.

The floating diffusion portion FD holds charge transferred from thephotoelectric converters PDA, PDB, PDC, and PDD and sets its voltage toa predetermined voltage in accordance with the capacitance value of thefloating diffusion portion FD and the amount of transferred charge. Thereset transistor M2 is controlled by the control signal PRES and, whenturned on, resets the floating diffusion portion FD to a predeterminedvoltage in accordance with the voltage Vdd.

The amplifier transistor M3 is configured such that the voltage Vdd issupplied to the drain and a bias current is supplied to the source fromthe current source 18 via the output line 16 and forms an amplifier unit(source follower circuit) whose gate is the input node. Thereby, theamplifier transistor M3 outputs, to the output line 16, a signal inaccordance with the amount of charge generated by incident light to thephotoelectric converters PDA, PDB, PDC, and PDD. Note that, in thisspecification, the amplifier transistor M3 may be referred to as anoutput unit.

When, out of the transfer transistors M1A to M1D, any one or moretransfer transistors M1 associated with an operation mode are turned on,charge of the photoelectric converter PD connected to the turned-ontransfer transistor M1 is transferred to the floating diffusion portionFD. For example, when only the transfer transistor M1A is turned on,charge held in the photoelectric converter PDA is transferred to thefloating diffusion portion FD, and a signal in accordance with theamount of charge generated by incident light to the photoelectricconverter PDA is output to the output line 16. Further, when all thetransfer transistors M1A to M1D are turned on, charges held in thephotoelectric converters PDA to PDD are added in the floating diffusionportion FD, and a signal in accordance with the total amount of chargesgenerated by the incident light to the photoelectric converters PDA toPDD is output to the output line 16.

The signal output to the output line 16 is input to the column amplifier42 via the switch SW1 and converted into a digital signal by an ADconverter (not illustrated) arranged on the post-stage thereof.

Note that each of the unit pixels 12 includes four pixels correspondingto each of the four photoelectric converters PDA, PDB, PDC, and PDD. Inthese four pixels, a first pixel is formed of the photoelectricconverter PDA, the transfer transistor M1A, the reset transistor M2, andthe amplifier transistor M3. A second pixel is formed of thephotoelectric converter PDB, the transfer transistor M1B, the resettransistor M2, and the amplifier transistor M3. A third pixel is formedof the photoelectric converter PDC, the transfer transistor M1C, thereset transistor M2, and the amplifier transistor M3. A fourth pixel isformed of the photoelectric converter PDD, the transfer transistor M1D,the reset transistor M2, and the amplifier transistor M3. These fourpixels share the floating diffusion portion FD, the reset transistor M2,and the amplifier transistor M3.

The pixel region 10 is formed by arranging a unit blocks 20 illustratedin FIG. 3 repeatedly in the row direction and the column direction. Thatis, the unit block 20 is the minimum repetition unit in the pixel region10.

The unit block 20 is formed of four unit pixels 12 arranged in a matrixof two rows by two columns. One unit pixel 12 includes four pixelsarranged in a matrix of two rows by two columns. In the followingdescription, when a row and a column of the unit pixels 12 areexpressed, expressions of “unit pixel row” and “unit pixel column” areused, and when a row and a column of pixels included in the unit pixel12 are expressed, expressions of “pixel row” and “pixel column” areused. That is, the unit block 20 includes four unit pixels 12 arrangedin a matrix of two unit pixel rows by two unit pixel columns. Further,the unit block 20 includes 16 pixels arranged in a matrix of 4 pixelrows by 4 pixel columns.

Each of the 16 pixels arranged in the unit block 20 includes a colorfilter having a predetermined spectral sensitivity characteristic. Eachof the characters “R”, “Gr”, “Gb”, “B”, and “W” illustrated in FIG. 3represents a spectral sensitivity characteristic of a color filterprovided to the corresponding pixel. That is, “R” represents a redfilter, “Gr” and “Gb” each represent a green filter, “B” represents ablue filter, and “W” represents a white filter. The filters “Gr” and“Gb” are green filters having the same spectral sensitivitycharacteristic. To distinguish the two green filters included in asingle unit block 20 from each other, a green filter arranged on thesame pixel column as a red filter R is denoted as “Gr”, and a greenfilter arranged on the same pixel column as a blue filter B is denotedas “Gb” for the purpose of illustration.

In the following description, a pixel provided with a red filter R isdenoted as an R pixel, a pixel provided with a green filter Gr or Gb isdenoted as an Gr or Gb pixel or correctively denoted as a G pixel, and apixel provided with a blue filter B is denoted as an B pixel. The Rpixel, the G pixel, and the B pixel are pixels mainly for outputtingcolor information and may be referred to as “color pixel” or “RGBpixel”. Further, a pixel provided with a white filter W is denoted as aW pixel. The W pixel is a pixel for mainly outputting luminanceinformation and may be referred to as “white pixel” or “clear pixel”.

Note that the W pixel is a pixel that directly detects an incident lightwithout color separation. The W pixel is featured in that thetransmission wavelength range is wider and the sensitivity is higherthan those of the R pixel, the G pixel, and the B pixel in the spectralsensitivity characteristic, and, the W pixel has the wavelength widestfull width at half maximum of a transmission wavelength range in thespectral sensitivity characteristic, for example. Typically, thetransmission wavelength range in the spectral sensitivity characteristicof the W pixel covers the transmission wavelength range in the spectralsensitivity characteristic of the R pixel, the G pixel, and the B pixel.

Note that, in FIG. 3, the R pixel is labeled with the reference 22R, theGr pixel is labeled with the reference 22Gr, the Gb pixel is labeledwith the reference 22Gb, the B pixel is labeled with the reference 22B,and the W pixel is labeled with the reference 22W. In the followingdescription, when collectively illustrated, the R pixel 22R, the Grpixel 22Gr, the Gb pixel 22Gb, the B pixel 22B, and the W pixel 22W maybe denoted as the pixel 22.

In the color filter arrangement illustrated in FIG. 3, out of 16 pixelsincluded in the unit block 20, the ratio of the R pixel, the G pixel,the B pixel, and W pixel is R:G:B:W=1:2:1:12. Such color filterarrangement having 12 W pixels in the unit block 20 is denoted as“RGBW12 arrangement” in this specification. In the RGBW12 arrangement,the ratio of color pixels and W pixels is RGB:W=1:3. The feature of theRGBW12 arrangement may be that every color pixel of the R pixel, the Gpixel, and the B pixel is surrounded by the W pixels and that theoccupancy ratio of the W pixels in all the pixels is 3/4.

As illustrated in FIG. 3, each of the four unit pixels 12 forming theunit block 20 includes one color pixel and three W pixels. The unitpixel 12 including the R pixel 22R and the unit pixel 12 including the Bpixel 22B are arranged at positions in one of the diagonal directions ofthe unit block 20. Further, the unit pixel 12 including the Gr pixel22Gr and the unit pixel 12 including the Gb pixel 22Gb are arranged atpositions in the other diagonal direction of the unit block 20. Thepositions of color pixels within the unit pixel 12 are the same for allthe unit pixels 12. Further, four pixels 22 included in each of the unitpixels 12 share one floating diffusion portion FD as described above.The floating diffusion portion FD may be arranged at the center of theunit pixel 12.

With such arrangement of color pixels and the floating diffusion portionFD, the R pixel 22R, the Gr pixel 22Gr, the Gb pixel 22Gb, and the Bpixel 22B are arranged equally to the Bayer arrangement in terms of thepositional relationship of being connected to the floating diffusionportion FD of the unit pixels 12 to which respective pixels belong.

By arranging the pixels 22 in such a way, it is possible to add a signalof one color pixel and signals of three W pixels when adding (alsoreferred to as binning) signals in the floating diffusion portion FD forthe purpose of improvement of sensitivity. In such a case, while thesignal of the color pixel is mixed with the signals of the W pixels,signals of color pixels of different colors are separated from eachother. It is therefore possible to obtain independent information on acolor pixel for each color and ensure color reproducibility.

Next, the configuration of floating diffusion portions FD shared by fourpixels 22 included in a single unit pixel 12 will be described in moredetail with reference to FIG. 4.

FIG. 4 illustrates a plan layout of four pixels 22 a, 22 b, 22 c, and 22d included in one unit pixel 12. The pixel 22 a includes thephotoelectric converter PDA and the transfer transistor M1A. The pixel22 b includes the photoelectric converter PDB and the transfertransistor M1B. The pixel 22 c includes the photoelectric converter PDCand the transfer transistor M1C. The pixel 22 d includes thephotoelectric converter PDD and the transfer transistor M1D. Thetransfer transistors M1A, M1B, M1C, and M1D include gate electrodes(transfer gates) 24A, 24B, 24C, and 24D, respectively.

In the floating diffusion portion FD, it is desirable to reduce the areaas much as possible to reduce the parasitic capacitance. This isbecause, when noise on the post-stage of a pixel amplifier (sourcefollower circuit) is converted into the input of the floating diffusionportion FD (converted into the number of electrons), the noise convertedinto the number of electrons appears to be large and the S/N ratiodecreases when the parasitic capacitance of the floating diffusionportion FD is large. The reduced S/N ratio deteriorates the lowestobject illuminance that indicates the ability of capturing a darkerplace.

In the present embodiment, in terms of reducing the capacitance of thefloating diffusion portion FD, the floating diffusion portion FD isformed of a single continuous impurity diffusion region and shared byfour pixels 22. This is because, when the floating diffusion portion FDis formed by two or more impurity floating diffusion regions beingconnected by interconnections, the parasitic capacitance coupled to theinterconnections is superimposed, and the capacitance of the floatingdiffusion portion FD increases.

Further, in the present embodiment, the gate width directions of thetransfer transistors M1A, M1B, M1C, and M1D are the same, and thedirection of charge transfer from the photoelectric converter PD to thefloating diffusion portion FD is limited to the vertical direction inFIG. 4. This is because of consideration for a situation where, in termsof improvement of the charge transfer performance from the photoelectricconverter PD to the floating diffusion portion FD or the like, ionimplantation in forming the photoelectric converter PD or the floatingdiffusion portion FD may be performed from a direction diagonal to thenormal direction of the substrate. With the gate width direction of thefour transfer transistors M1A, M1B, M1C, and M1D being the same,variation of the transfer performance of these transistors can bereduced.

Next, a method of driving the imaging device according to the presentembodiment will be described with reference to FIG. 5 to FIG. 9. FIG. 5and FIG. 6 are flowcharts illustrating methods of driving the imagingdevice according to the present embodiment. FIG. 7 is a diagramillustrating data arrangement when pixel addition is performed on a unitpixel basis in the method of driving the imaging device according to thepresent embodiment. FIG. 8 and FIG. 9 are diagrams illustrating colorinterpolation methods in the method of driving the imaging deviceaccording to the present embodiment.

In the present embodiment, a driving example of reading out data fromeach of the pixels 22 and a driving example of reading out added datafrom each of the unit pixels 12 will be described.

FIG. 5 illustrates a driving example when readout of data is performedfrom each of the pixels 22 (first driving example). In the first drivingexample, data readout operations are performed sequentially on a pixelrow basis. In this example, a case where data are read out from 16pixels 22 belonging to the unit block 20 illustrated in FIG. 3 will bedescribed as an example. In the unit block 20 illustrated in FIG. 3, theR pixel 22R, the W pixel 22W, the Gr pixel 22Gr, and the W pixel 22W arearranged in this order on the first pixel row. Further, four W pixels22W are arranged on the second pixel row and the fourth pixel row.Further, the Gb pixel 22Gb, the W pixel 22W, the B pixel 22B, and the Wpixel 22W are arranged in this order on the third pixel row.

First, readout of data from the R pixel 22R, the W pixel 22W, the Grpixel 22Gr, and the W pixel 22W is performed on the first pixel row(step S101). Specifically, after each floating diffusion portion FD isreset, the transfer transistor M1A of each unit pixel 12 is driven totransfer charge of the photoelectric converter PDA to the floatingdiffusion portion FD and read out the data of the R pixel 22R and thedata of the Gr pixel 22Gr. Subsequently, after each floating diffusionportion FD is reset, the transfer transistor M1B of each unit pixel 12is driven to transfer charge of the photoelectric converter PDB to thefloating diffusion portion FD and read out data of the W pixel 22W onthe second pixel column and data of the W pixel 22W on the fourth pixelcolumn.

Next, readout of data from the W pixel 22W, the W pixel 22W, the W pixel22W, and the W pixel 22W is performed on the second pixel row (stepS102). Specifically, after each floating diffusion portion FD is reset,the transfer transistor M1C of each unit pixel 12 is driven to transfercharge of the photoelectric converter PDA to the floating diffusionportion FD and read out the data of the W pixel 22W on the first pixelcolumn and the data of the W pixel 22W on the third pixel column.Subsequently, after each floating diffusion portion FD is reset, thetransfer transistor M1D of each unit pixel 12 is driven to transfercharge of the photoelectric converter PDB to the floating diffusionportion FD and read out data of the W pixel 22W on the second pixelcolumn and data of the W pixel 22W on the fourth pixel column.

Next, readout of data from the Gb pixel 22Gb, the W pixel 22W, the Bpixel 22B, and the W pixel 22W is performed on the third pixel row (stepS103). Specifically, after each floating diffusion portion FD is reset,the transfer transistor M1A of each unit pixel 12 is driven to transfercharge of the photoelectric converter PDA to the floating diffusionportion FD and read out the data of the Gb pixel 22Gb and the data ofthe B pixel 22B. Subsequently, after each floating diffusion portion FDis reset, the transfer transistor M1B of each unit pixel 12 is driven totransfer charge of the photoelectric converter PDB to the floatingdiffusion portion FD and read out data of the W pixel 22W on the secondpixel column and data of the W pixel 22W on the fourth pixel column.

Next, readout of data from the W pixel 22W, the W pixel 22W, the W pixel22W, and the W pixel 22W is performed on the fourth pixel row (stepS104). Specifically, after each floating diffusion portion FD is reset,the transfer transistor M1C of each unit pixel 12 is driven to transfercharge of the photoelectric converter PDA to the floating diffusionportion FD and read out the data of the W pixel 22W on the first pixelcolumn and the data of the W pixel 22W on the third pixel column.Subsequently, after each floating diffusion portion FD is reset, thetransfer transistor M1D of each unit pixel 12 is driven to transfercharge of the photoelectric converter PDB to the floating diffusionportion FD and read out data of the W pixel 22W on the second pixelcolumn and data of the W pixel 22W on the fourth pixel column.

Next, a high accuracy interpolation process (step S105) and a colorcomposition process (step S106) are performed on the read out data. Notethat a known method, for example, the method disclosed in JapanesePatent Application Laid-Open No. 2016-213715 can be applied for the highaccuracy interpolation process and the color composition process. In thepresent embodiment, since the RGBW12 arrangement is used as color filterarrangement, an image with high sensitivity can be acquired by usingdata of W pixels.

FIG. 6 illustrates a driving example when readout of added data isperformed from each of the unit pixels 12 (second driving example). Inthe second driving example, data readout operations are performedsequentially on a unit pixel row basis. In this example, a case whereadded data are read out from four unit pixels 12 belonging to the unitblock 20 illustrated in FIG. 3 will be described as an example. In theunit block 20 illustrated in FIG. 3, the unit pixel 12 including one Rpixel 22R and three W pixels 22W and the unit pixel 12 including one Grpixel 22Gr and three W pixels 22W are arranged on the first unit pixelrow. Further, the unit pixel 12 including one Gb pixel 22Gb and three Wpixels 22W and the unit pixel 12 including one B pixel 22B and three Wpixels 22W are arranged on the second unit pixel row. According to thesecond driving example, an image with higher sensitivity can be acquiredthan in the first driving example.

First, readout of data (R+W3) in which a signal of the R pixel 22R andsignals of the three W pixels 22W are added and data (Gr+W3) in which asignal of the Gr pixel 22Gr and signals of the three W pixels 22W areadded is performed on the first unit pixel row (step S201).Specifically, after each floating diffusion portion FD is reset, thetransfer transistors M1A, M1B, M1C, and M1D of each unit pixel 12 aredriven to transfer charges of the photoelectric converters PDA, PDB,PDC, and PDD to the floating diffusion portion FD. Thereby, data (R+W3)in which the signal of R pixel 22R and the signals of the three W pixels22W are added is read out from the unit pixel 12 on the first unit pixelcolumn. Further, data (Gr+W3) in which the signal of Gr pixel 22Gr andthe signals of the three W pixels 22W are added is read out from theunit pixel 12 on the second unit pixel column.

Next, readout of data (Gb+W3) in which a signal of the Gb pixel 22Gb andsignals of the three W pixels 22W are added and data (B+W3) in which asignal of the B pixel 22B and signals of the three W pixels 22W areadded is performed on the second unit pixel row (step S202).Specifically, after each floating diffusion portion FD is reset, thetransfer transistors M1A, M1B, M1C, and M1D of each unit pixel 12 aredriven to transfer charges of the photoelectric converters PDA, PDB,PDC, and PDD to the floating diffusion portion FD. Thereby, data (Gb+W3)in which the signal of Gb pixel 22Gb and the signals of the three Wpixels 22W are added is read out from the unit pixel 12 on the firstunit pixel column. Further, data (B+W3) in which the signal of B pixel22B and the signals of the three W pixels 22W are added is read out fromthe unit pixel 12 on the second unit pixel column.

FIG. 7 illustrates data arrangement when readout of a region of six unitpixel rows by six unit pixel columns is performed by using the seconddriving example. All the data read out from each of the unit pixels 12will be data of a color pixel+W pixel×3, as illustrated in FIG. 7.

When data is read out by performing pixel addition in such a way and ifnoise levels occurring in the floating diffusion portions FD are thesame regardless of whether or not the addition is performed, the chargeamount transferred to the floating diffusion portion FD is approximatelythree to four times, and thus the SN ratio can be improved.

Next, a demosaic process is performed on the read out data. Thearrangement of data read out by the second driving example is the samearrangement as the Bayer arrangement while data of W pixels are added,as illustrated in FIG. 7. Therefore, when performing a color developingprocess in the second driving example, it is possible to performinterpolation of respective color pixels by the same method as that forthe Bayer arrangement.

In a demosaic process, first, a color interpolation process is performedby using data read out in step S201 and step S202 (step S203). Here, anexample using a bilinear method will be described as a method of thecolor interpolation process. The bilinear method is a method forcalculating an interpolation value by averaging data of pixels of thesame color arranged nearby.

Note that, in the following description, the unit pixel 12 from whichdata of R+W3 is read out may be denoted as “R+W3 unit pixel”. Further,the unit pixel 12 from which data of Gr+W3 is read out may be denoted as“Gr+W3 unit pixel”. Further, the unit pixel 12 from which data of Gb+W3is read out may be denoted as “Gb+W3 unit pixel”. Further, the unitpixel 12 from which data of B+W3 is read out may be denoted as “B+W3unit pixel”. Further, the unit pixel 12 from which data of Gr+W3 is readout and the unit pixel 12 from which data of Gr+W3 is read out may becollectively denoted as “G+W3 unit pixel”.

First, a color interpolation method of data of G (green) will bedescribed. As described above, since the Gr pixel and the Gb pixel havesubstantially the same characteristics, the Gr pixels and the Gb pixelsform G pixels arranged in a checkered pattern when viewed as a whole.Therefore, an interpolation value of G (interpolation G+W3) in the R+W3unit pixel and the B+W3 unit pixel can be calculated by averaging dataof four G+W3 unit pixels located on the upper side, the lower side, theleft side, and the right side, as illustrated in FIG. 8.

Next, a color interpolation method of data of B (blue) will bedescribed. Since, unlike the G+W3 unit pixel, one B+W3 unit pixel isincluded in each unit block 20, it is necessary to use a colorinterpolation method different from the color interpolation method ofthe interpolation a G+W3 described above. That is, with respect to Gr+W3unit pixel, since B+W3 unit pixels are located on the upper side and thelower side thereof, an interpolation value of B (interpolation B+W3) canbe calculated by averaging data of these two B+W3 unit pixels, asillustrated with two arrows on the left side in FIG. 9. Similarly, withrespect to a Gb+W3 unit pixel, since B+W3 unit pixels are located on theleft side and the right side thereof, an interpolation value of B(interpolation B+W3) can be calculated by averaging data of these twoB+W3 unit pixels. Further, with respect to an R+W3 unit pixel, sinceB+W3 unit pixels are located in four diagonal directions, aninterpolation value of B (interpolation B+W3) can be calculated byaveraging data of these four B+W3 unit pixels, as illustrated with fourarrows on the right side in FIG. 9.

With respect to data of R (red), the color interpolation can beperformed by using the same scheme as the color interpolation method ofdata of B (interpolation B+W3).

Color interpolation processes are performed on all the unit pixels 12 insuch a way, and thus each of unit pixels 12 will have three types ofvalues, namely, data of R (R+W3), data of G (G+W3), and data of B(B+W3).

Next, color difference information at each unit pixel 12 is created(step S204). That is, the color value is calculated from three types ofvalues provided in the unit pixel 12 with respect to each of the unitpixels 12. While each of data of R+W3, G+W3, and B+W3 includes colorinformation, data of W is dominant in a signal intensity, it is notpreferable to directly use each data in terms of color reproducibility.

Accordingly, color information of each unit pixel 12, that is, colordifference data between R and G and color difference data between B andG are acquired by performing calculation below.Color difference (R−G)=(R+W3)−(G+W3)Color difference (B−G)=(B+W3)−(G+W3)

Further, as another method, it is possible to acquire color informationby performing calculation below. Here, each of K1, K2, K3, K4, and K5 isa constant and varies in accordance with the spectral sensitivitycharacteristic of each color or a property of a light source.Luminance: Y=K1×(R+W3)+K2(G+W3)+K3(B+W3)Color difference: PR=K4×((R+W3)−Y)Color difference: PB=K5×((R+W3)−Y)

In such a way, by extracting color information from data of the unitpixel 12 in which data of W is mixed, it is possible to improve colorreproducibility.

In the present embodiment, in the imaging device having color filters ofthe RGBW12 arrangement, the unit pixel 12 is formed of one color pixeland three W pixels that share the floating diffusion portion FD and theoutput unit, and thus improvement of sensitivity by binning can berealized. Further, each of the unit pixels 12 includes only one colorpixel, and thus the color reproducibility is not reduced by the binning.

To examine the effect and advantage of the present embodiment,evaluation capturing related to the dark view performance was performedby using the drive method described above. As a comparative example, thesame evaluation capturing was performed also in an imaging device havingcolor filter arrangement of RGGB arrangement (normal Bayer arrangement).As a result, in the imaging device of the present embodiment using theRGBW12 arrangement, with respect to the lowest object illuminance(brightness at which a ratio of an output signal and noise for acaptured object is 1:1), capturing was successfully performed at up tohalf the brightness of the case of the comparative example. Further, byfurther performing pixel addition, capturing was successfully performedup to further half the brightness, and preferable color reproducibilitycan be obtained.

As described above, according to the present embodiment, it is possibleto improve sensitivity without deteriorating color reproducibility andacquire an image with a high S/N ratio.

Second Embodiment

An imaging device and a method of driving the same according to a secondembodiment of the present disclosure will be described with reference toFIG. 10 and FIG. 11. The same component as that in the imaging deviceaccording to the first embodiment is labeled with the same reference,and the description thereof will be omitted or simplified. FIG. 10 is aflowchart illustrating the method of driving the imaging deviceaccording to the present embodiment. FIG. 11 is a diagram illustrating acolor interpolation method in the method of driving the imaging deviceaccording to the present embodiment.

In the present embodiment, an example of acquiring data of W (W3) inaddition to three types of data of R (R+W3), data of G (G+W3), and dataof B (B+W3) to obtain color data of primary colors instead of colordifference information will be described.

In the method of driving the imaging device according to the presentembodiment, as illustrated in FIG. 10, data readout operations areperformed sequentially on a unit pixel row basis in the same manner asthe second drive method of the first embodiment.

First, readout of data (R+W3) in which a signal of an R pixel 22R andsignals of three W pixels 22W are added and data (Gr+W3) in which asignal of a Gr pixel 22Gr and signals of three W pixels 22W are added isperformed on the first unit pixel row (step S301). Specifically, aftereach floating diffusion portion FD is reset, the transfer transistorsM1A, M1B, M1C, and M1D of each unit pixel 12 are driven to transfercharges of the photoelectric converters PDA, PDB, PDC, and PDD to thefloating diffusion portion FD. Thereby, data (R+W3) in which the signalof the R pixel 22R and the signals of the three W pixels 22W are addedis read out from the unit pixel 12 on the first unit pixel column.Further, data (Gr+W3) in which the signal of the Gr pixel 22Gr and thesignals of the three W pixels 22W are added is read out from the unitpixel 12 on the second unit pixel column.

Next, readout of data (W3) in which only signals of three W pixels 22Ware added and data (B+W3) in which a signal of a B pixel 22B and signalsof three W pixels 22W are added is performed on the second unit pixelrow (step S302). Specifically, after each floating diffusion portion FDis reset, the transfer transistors M1B, M1C, and M1D of each unit pixel12 are driven to transfer charges of the photoelectric converters PDB,PDC, and PDD to the floating diffusion portion FD. Thereby, data (W3) inwhich the signal of the three W pixels 22W are added is read out fromthe unit pixel 12 on the second unit pixel column. Subsequently, thetransfer transistor M1A of each unit pixel 12 is driven to transfercharge of the photoelectric converter PDA to the floating diffusionportion FD. Thereby, data (B+W3) in which the signal of the B pixel 22Band the signals of the three W pixels 22W are added is read out from theunit pixel 12 on the second unit pixel column. Note that the transfertransistor M1A of the unit pixel 12 on the first unit pixel column andthe transfer transistor M1A of the unit pixel 12 on the second unitpixel column may be controlled by different control signals toselectively drive the transfer transistor M1A of the unit pixel 12 onthe second unit pixel column.

When data is read out by performing pixel addition in such a way and ifnoise levels occurring in the floating diffusion portions FD are thesame regardless of whether or not the addition is performed, the chargeamount transferred to the floating diffusion portion FD is approximatelythree to four times, and thus the SN ratio can be improved.

Next, a color interpolation process is performed by using data read outin step S301 and step S302 (step S303). Note that, in the followingdescription, the unit pixel 12 from which data of W3 is read out may bedenoted as “W3 unit pixel”.

In the present embodiment, since data (G+W3) of G is not arranged in acheckered pattern, a color interpolation process is performed by using abilinear method also for data of G as with data of R and data of B.Further, in the present embodiment, the same color interpolation processas that for color data is performed for data of W (W3). One W3 unitpixel is included in each unit block 20 as with the R+W3 unit pixel, theGr+W3 unit pixel, and B+W3 unit pixel. Therefore, the same colorinterpolation process as that for data of R, data of G, and data of Bcan be performed also for such data of W.

That is, with respect to an R+W3 unit pixel, since W3 unit pixels arelocated on the upper side and the lower side thereof, an interpolationvalue of W (interpolation W3) can be calculated by averaging data ofthese two W3 unit pixels, as illustrated with two arrows on the leftside in FIG. 11. Similarly, with respect to a B+W3 unit pixel, since W3unit pixels are located on the left side and the right side thereof, aninterpolation value of W (interpolation W3) can be calculated byaveraging data of these two W3 unit pixels. Further, with respect to aGr+W3 unit pixel, since W3 unit pixels are located in four diagonaldirections, an interpolation value of W (interpolation W3) can becalculated by averaging data of these four W3 unit pixels, asillustrated with four arrows on the right side in FIG. 11.

Color interpolation processes are performed on all the unit pixels 12 insuch a way, and thus each of unit pixels 12 will have four types ofvalues, namely, data of R (R+W3), data of G (G+W3), data of B (B+W3),and data of W (W3).

Next, color difference information for each unit pixel 12 is created(step S304). That is, for each of the unit pixels 12, values of R, G,and B are acquired, respectively, by performing calculation below byusing four types of values provided in the unit pixel.R=(R+W3)−(W3)G=(G+W3)−(W3)B=(B+W3)−(W3)

Further, for the luminance Y at each unit pixel 12, data of W (W3) ofthe unit pixel may be used. Alternatively, the luminance Y can beacquired by performing calculation below. Here, each of K6, K7, K8, andK9 is a constant.Y=K6×(R+W3)+K7×(Gr+W3)+K8×(B+W3)+K9×(W3)

The final pixel value at unit pixel 12 can be calculated by multiplyingthe values of R, G, and B by the luminance Y.

As described above, according to the present embodiment, it is possibleto improve sensitivity without deteriorating color reproducibility andacquire an image with a high S/N ratio.

Third Embodiment

An imaging device and a method of driving the same according to a thirdembodiment of the present disclosure will be described with reference toFIG. 12. The same component as that in the imaging device according tothe first and second embodiments is labeled with the same reference, andthe description thereof will be omitted or simplified. FIG. 12 is a planview illustrating a unit block of a pixel region in the imaging deviceaccording to the present embodiment.

While W pixels are used as pixels from which luminance information isacquired in the first and second embodiments, it is possible to use Gpixels instead of W pixels. In the present embodiment, an example inwhich G pixels are used as pixels from which luminance information isacquired will be described.

The unit blocks 20 illustrated in FIG. 12 are repeatedly arranged in therow direction and the column direction, and thereby the pixel region 10of the imaging device according to the present embodiment is formed.That is, the unit block 20 is the minimum repetition unit in the pixelregion 10.

Each of 16 pixels arranged in the unit block 20 includes a color filterhaving a predetermined spectral sensitivity characteristic. Each of thecharacters “R”, “G”, and “B” illustrated in FIG. 12 represents aspectral sensitivity characteristic of a color filter provided to thecorresponding pixel. That is, “R” represents a red filter, “G”represents a green filter, and “B” represents a blue filter. In FIG. 12,an R pixel is denoted as the reference 22R, a G pixel is denoted as thereference 22G, and a B pixel is denoted as the reference 22B. In thecolor filter arrangement of the present embodiment illustrated in FIG.12, out of 16 pixels included in the unit block 20, the ratio of the Rpixel, the G pixel, and the B pixel is R:G:B=1:14:1.

Further, one unit block 20 includes one unit pixel 12 including one Rpixel 22R and three G pixels 22G, one unit pixel 12 including one Bpixel 22B and three G pixels 22G, and two unit pixels 12 including fourG pixels 22G. It is possible to acquire data of R+G3, data of B+G3, anddata of G4 from these unit pixels 12 by performing pixel addition.

Therefore, also in the imaging device according to the presentembodiment, a color difference signal can be acquired by performingcalculation below after interpolating three types of values of R+G3,B+G3, and G4 for each unit pixel 12 by the bilinear method in the samemanner as in the first embodiment.Color difference (R−G)=(R+G3)−(G4)Color difference (B−G)=(B+G3)−(G4)

As described above, according to the present embodiment, it is possibleto improve sensitivity without deteriorating color reproducibility andacquire an image with a high S/N ratio.

Fourth Embodiment

An imaging device and a method of driving the same according to a fourthembodiment of the present disclosure will be described with reference toFIG. 13 to FIG. 15. The same component as that in the imaging deviceaccording to the first to third embodiments is labeled with the samereference, and the description thereof will be omitted or simplified.FIG. 13 is a circuit diagram illustrating a configuration example of aunit pixel of the imaging device according to the present embodiment.FIG. 14 and FIG. 15 are timing diagrams illustrating methods of drivingthe imaging device according to the present embodiment.

As illustrated in FIG. 13, the imaging device according to the presentembodiment is the same as the imaging device according to the firstembodiment except that a column amplifier 44 is further connected to theoutput line 16 via the switch SW2. A signal output to the output line 16is input to the column amplifier 44 via the switch SW2 and convertedinto a digital signal by an AD converter (not illustrated) arranged onthe post-stage thereof. The switch SW2 and the column amplifier 44 are apart of the components of the readout circuit 40 as with the switch SW1and the column amplifier 42.

Next, the method of driving the imaging device according to the presentembodiment will be described with reference to FIG. 14 and FIG. 15. Thetiming diagrams of FIG. 14 and FIG. 15 indicate the control signalsPRES, PTXA, PTXB, PTXC, and PTXD, a control signal PSW1 for the switchSW1, and a control signal PSW2 for the switch SW2. When each of thesecontrol signals is at a high (H) level, the corresponding transistor orswitch is in an on-state, and when each of these control signals is at alow (L) level, the corresponding transistor or switch is in anoff-state.

First, the driving example when readout of data is performed from eachof the pixels 22 (first driving example) will be described withreference to FIG. 14.

At time t1, the vertical scanning circuit 30 controls the control signalPRES from the L level to the H level and then controls the controlsignal PRES from the H level to the L level. Thereby, during the periodin which the control signal PRES is at the H level, the reset transistorM2 is in the on-state, and the floating diffusion portion FD is reset toa voltage in accordance with the voltage Vdd.

Next, at time t2, the vertical scanning circuit 30 controls the controlsignal PTXA from the L level to the H level and then controls thecontrol signal PTXA from the H level to the L level. Thereby, during theperiod in which the control signal PTXA is at the H level, the transfertransistor M1A is in the on-state, and charge accumulated in thephotoelectric converter PDA is transferred to the floating diffusionportion FD.

Next, at time t3, the control circuit 70 controls the control signalPSW1 from the L level to the H level and then controls the controlsignal PSW1 from the H level to the L level. Thereby, during the periodin which the control signal PSW1 is at the H level, the switch SW1 is inthe on-state, and a signal in accordance with the amount of chargeaccumulated in the photoelectric converter PDA is output from theamplifier transistor M3 to the column amplifier 42 via the output line16 and the switch SW1. Then, the switch SW1 is turned off, and therebyan output signal from the amplifier transistor M3 is held in the columnamplifier 42.

Next, at time t4, the vertical scanning circuit 30 controls the controlsignal PRES from the L level to the H level and then controls thecontrol signal PRES from the H level to the L level. Thereby, during theperiod in which the control signal PRES is at the H level, the resettransistor M2 is in the on-state, and the floating diffusion portion FDis reset to the voltage in accordance with the voltage Vdd.

Next, at time t5, the vertical scanning circuit 30 controls the controlsignal PTXB from the L level to the H level and then controls thecontrol signal PTXB from the H level to the L level. Thereby, during theperiod in which the control signal PTXB is at the H level, the transfertransistor M1B is in the on-state, and charge accumulated in thephotoelectric converter PDB is transferred to the floating diffusionportion FD.

Next, at time t6, the control circuit 70 controls the control signalPSW2 from the L level to the H level and then controls the controlsignal PSW2 from the H level to the L level. Thereby, during the periodin which the control signal PSW2 is at the H level, the switch SW2 is inthe on-state, and a signal in accordance with the amount of chargeaccumulated in the photoelectric converter PDB is output from theamplifier transistor M3 to the column amplifier 44 via the output line16 and the switch SW2. Then, the switch SW2 is turned off, and therebyan output signal from the amplifier transistor M3 is held in the columnamplifier 44.

The signals held in the column amplifiers 42 and 44 are then convertedinto digital data, respectively, by an AD converter (not illustrated)arranged on the post-stage.

Next, at time t7, the vertical scanning circuit 30 controls the controlsignal PRES from the L level to the H level and then controls thecontrol signal PRES from the H level to the L level. Thereby, during theperiod in which the control signal PRES is at the H level, the resettransistor M2 is in the on-state, and the floating diffusion portion FDis reset to the voltage in accordance with the voltage Vdd.

Next, at time t8, the vertical scanning circuit 30 controls the controlsignal PTXC from the L level to the H level and then controls thecontrol signal PTXC from the H level to the L level. Thereby, during theperiod in which the control signal PTXC is at the H level, the transfertransistor M1C is in the on-state, and charge accumulated in thephotoelectric converter PDC is transferred to the floating diffusionportion FD.

Next, at time t9, the control circuit 70 controls the control signalPSW1 from the L level to the H level and then controls the controlsignal PSW1 from the H level to the L level. Thereby, during the periodin which the control signal PSW1 is at the H level, the switch SW1 is inthe on-state, and a signal in accordance with the amount of chargeaccumulated in the photoelectric converter PDC is output from theamplifier transistor M3 to the column amplifier 42 via the output line16 and the switch SW1. Then, the switch SW1 is turned off, and therebyan output signal from the amplifier transistor M3 is held in the columnamplifier 42.

Next, at time t10, the vertical scanning circuit 30 controls the controlsignal PRES from the L level to the H level and then controls thecontrol signal PRES from the H level to the L level. Thereby, during theperiod in which the control signal PRES is at the H level, the resettransistor M2 is in the on-state, and the floating diffusion portion FDis reset to the voltage in accordance with the voltage Vdd.

Next, at time t11, the vertical scanning circuit 30 controls the controlsignal PTXD from the L level to the H level and then controls thecontrol signal PTXD from the H level to the L level. Thereby, during theperiod in which the control signal PTXD is at the H level, the transfertransistor M1D is in the on-state, and charge accumulated in thephotoelectric converter PDD is transferred to the floating diffusionportion FD.

Next, at time t12, the control circuit 70 controls the control signalPSW2 from the L level to the H level and then controls the controlsignal PSW2 from the H level to the L level. Thereby, during the periodin which the control signal PSW2 is at the H level, the switch SW2 is inthe on-state, and a signal in accordance with the amount of chargeaccumulated in the photoelectric converter PDD is output from theamplifier transistor M3 to the column amplifier 44 via the output line16 and the switch SW2. Then, the switch SW2 is turned off, and therebyan output signal from the amplifier transistor M3 is held in the columnamplifier 44.

The signals held in the column amplifiers 42 and 44 are then convertedinto digital data, respectively, by an AD converter (not illustrated)arranged on the post-stage.

By driving the imaging device in such a way, it is possible to read outsignals in accordance with the amount of charges accumulated in the fourphotoelectric converters PDA, PDB, PDC, and PDD, respectively andindependently. Further, since signals of pixels arranged on the samepixel row are AD-converted at the same time, this simplifies alignmentof data in a signal processing unit (not illustrated), and a process ofcolor development or the like becomes easier.

Next, the driving example when readout of added data is performed fromeach of the unit pixel 12 (second driving example) will be describedwith reference to FIG. 15.

At time t1, the vertical scanning circuit 30 controls the control signalPRES from the L level to the H level and then controls the controlsignal PRES from the H level to the L level. Thereby, during the periodin which the control signal PRES is at the H level, the reset transistorM2 is in the on-state, and the floating diffusion portion FD is reset toa voltage in accordance with the voltage Vdd.

Next, at time t2, the vertical scanning circuit 30 controls the controlsignals PTXA, PTXB, PTXC, and PTXD from the L level to the H level andthen controls the control signals PTXA, PTXB, PTXC, and PTXD from the Hlevel to the L level. Thereby, during the period in which the controlsignals PTXA, PTXB, PTXC, and PTXD are at the H level, the transfertransistors M1A, M1B, M1C, and M1D are in the on-state, and chargesaccumulated in the photoelectric converters PDA, PDB, PDC, and PDD aretransferred to the floating diffusion portion FD.

Next, at time t3, the control circuit 70 controls the control signalPSW1 from the L level to the H level and then controls the controlsignal PSW1 from the H level to the L level. Thereby, during the periodin which the control signal PSW1 is at the H level, the switch SW1 is inthe on-state, and a signal in accordance with the total amount ofcharges accumulated in the photoelectric converters PDA, PDB, PDC, andPDD is output from the amplifier transistor M3 to the column amplifier42. Then, the switch SW1 is turned off, and thereby an output signalfrom the amplifier transistor M3 is held in the column amplifier 42.

The signal held in the column amplifier 42 is then converted intodigital data by an AD converter (not illustrated) arranged on thepost-stage.

By driving the imaging device in such a way, it is possible to read outsignals in accordance with the total amount of charges accumulated inthe four photoelectric converters PDA, PDB, PDC, and PDD as pixeladdition data. Thereby, capturing can be performed at up to half thebrightness compared to the case where no pixel addition is performed,and preferable color reproducibility can be obtained.

As described above, according to the present embodiment, it is possibleto improve sensitivity without deteriorating color reproducibility andacquire an image with a high S/N ratio.

Fifth Embodiment

An imaging device and a method of driving the same according to a fifthembodiment of the present disclosure will be described with reference toFIG. 16 to FIG. 18. The same component as that in the imaging deviceaccording to the first to fourth embodiments is labeled with the samereference, and the description thereof will be omitted or simplified.FIG. 16 is a circuit diagram illustrating a configuration example of aunit pixel of the imaging device according to the present embodiment.FIG. 17 and FIG. 18 are timing diagrams illustrating methods of drivingthe imaging device according to the present embodiment.

In the imaging device according to the first to fourth embodiments, fourpixels 22 forming one unit pixel 12 share the reset transistor M2, theamplifier transistor M3, and the output line 16. In contrast, in theimaging device according to the present embodiment, four pixels 22forming one unit pixel 12 are divided into two sets each sharing thereset transistor M2, the amplifier transistor M3, and the output line 16on a pixel column basis.

That is, as illustrated in FIG. 16, the unit pixel 12 of the presentembodiment includes the photoelectric converters PDA, PDB, PDC, and PDD,the transfer transistors M1A, M1B, M1C, and M1D, reset transistors M2Aand M2B, and amplifier transistors M3A and M3B.

In the photodiode of the photoelectric converter PDA, the anode isconnected to the ground voltage node, and the cathode is connected tothe source of the transfer transistor M1A. In the photodiode of thephotoelectric converter PDC, the anode is connected to the groundvoltage node, and the cathode is connected to the source of the transfertransistor M1C. The drains of the transfer transistors M1A and M1C areconnected to the source of the reset transistor M2A and the gate of theamplifier transistor M3A. The connection node of the drains of thetransfer transistors M1A and M1C, the source of the reset transistorM2A, and gate of the amplifier transistor M3A is a floating diffusionportion FDA. The source of the amplifier transistor M3A is connected toan output line 16A. The current source 18 is connected to the outputline 16A.

In the photodiode of the photoelectric converter PDB, the anode isconnected to the ground voltage node, and the cathode is connected tothe source of the transfer transistor M1B. In the photodiode of thephotoelectric converter PDD, the anode is connected to the groundvoltage node, and the cathode is connected to the source of the transfertransistor M1D. The drains of the transfer transistors M1B and M1D areconnected to the source of the reset transistor M2B and the gate of theamplifier transistor M3B. The connection node of the drains of thetransfer transistors M1B and M1D, the source of the reset transistorM2B, and gate of the amplifier transistor M3B is a floating diffusionportion FDB. The source of the amplifier transistor M3B is connected toan output line 16B. The current source 18 is connected to the outputline 16B.

The column amplifier 42 is connected to the output line 16A via theswitch SW1. The column amplifier 44 is connected to the output line 16Bvia the switch SW2. Further, a switch SW3 is connected between theoutput line 16A and the output line 16B. The switch SW3 is a switch usedfor artificially averaging a signal output from the amplifier transistorM3A and a signal output from the amplifier transistor M3B. The switchesSW1, SW2, and SW3 and the column amplifiers 42 and 44 are a part of thecomponents of the readout circuit 40.

In the case of the unit pixel 12 configured as illustrated in FIG. 16,the control line 14 arranged on each row of the pixel region 10 includesthree signal lines that supply the control signals PTXA, PTXC, and PRES.The signal line that supplies the control signal PTXA is connected tothe gates of the transfer transistors M1A and M1B of the unit pixels 12belonging to the corresponding row, respectively, to form a signal linecommon to these unit pixels 12. The signal line that supplies thecontrol signal PTXC is connected to the gates of the transfertransistors M1C and M1D of the unit pixels 12 belonging to thecorresponding row, respectively, to form a signal line common to theseunit pixels 12. The signal line that supplies the control signal PRES isconnected to the gates of the reset transistors M2 of the unit pixels 12belonging to the corresponding row, respectively, to form a signal linecommon to these unit pixels 12.

Other features of the imaging device according to the present embodimentare the same as those of the imaging device according to the firstembodiment.

Next, the method of driving the imaging device according to the presentembodiment will be described with reference to FIG. 17 and FIG. 18. Thetiming diagrams of FIG. 17 and FIG. 18 indicate the control signalsPRES, PTXA, and PTXC, a control signal PSW1 for the switch SW1, acontrol signal PSW2 for the switch SW2, and a control signal PSW3 forthe switch SW3. When each of these control signals is at a high (H)level, the corresponding transistor or switch is in an on-state, andwhen each of these control signals is at a low (L) level, thecorresponding transistor or switch is in an off-state.

First, the driving example when readout of data is performed from eachof the pixels 22 (first driving example) will be described withreference to FIG. 17.

At time t1, the vertical scanning circuit 30 controls the control signalPRES from the L level to the H level and then controls the controlsignal PRES from the H level to the L level. Thereby, during the periodin which the control signal PRES is at the H level, the resettransistors M2A and M2B are in the on-state, and the floating diffusionportions FDA and FDB are reset to a voltage in accordance with thevoltage Vdd.

Next, at time t2, the vertical scanning circuit 30 controls the controlsignal PTXA from the L level to the H level and then controls thecontrol signal PTXA from the H level to the L level. Thereby, during theperiod in which the control signal PTXA is at the H level, the transfertransistors M1A and M1B are in the on-state, charge accumulated in thephotoelectric converter PDA is transferred to the floating diffusionportion FDA, and charge accumulated in the photoelectric converter PDBis transferred to the floating diffusion portion FDB.

Next, at time t3, the control circuit 70 controls the control signalPSW1 from the L level to the H level and then controls the controlsignal PSW1 from the H level to the L level. Thereby, during the periodin which the control signal PSW1 is at the H level, the switch SW1 is inthe on-state, and a signal in accordance with the amount of chargeaccumulated in the photoelectric converter PDA is output from theamplifier transistor M3A to the column amplifier 42 via the output line16A and the switch SW1. Then, the switch SW1 is turned off, and therebyan output signal from the amplifier transistor M3A is held in the columnamplifier 42.

Similarly, at time t3, the control circuit 70 controls the controlsignal PSW2 from the L level to the H level and then controls thecontrol signal PSW2 from the H level to the L level. Thereby, during theperiod in which the control signal PSW2 is at the H level, the switchSW2 is in the on-state, and a signal in accordance with the amount ofcharge accumulated in the photoelectric converter PDB is output from theamplifier transistor M3B to the column amplifier 44 via the output line16B and the switch SW2. Then, the switch SW2 is turned off, and therebyan output signal from the amplifier transistor M3B is held in the columnamplifier 44.

The signals held in the column amplifiers 42 and 44 are then convertedinto digital data, respectively, by an AD converter (not illustrated)arranged on the post-stage.

Next, at time t4, the vertical scanning circuit 30 controls the controlsignal PRES from the L level to the H level and then controls thecontrol signal PRES from the H level to the L level. Thereby, during theperiod in which the control signal PRES is at the H level, the resettransistors M2A and M2B are in the on-state, and the floating diffusionportions FDA and FDB are reset to the voltage in accordance with thevoltage Vdd.

Next, at time t5, the vertical scanning circuit 30 controls the controlsignal PTXC from the L level to the H level and then controls thecontrol signal PTXC from the H level to the L level. Thereby, during theperiod in which the control signal PTXC is at the H level, the transfertransistors M1C and M1D are in the on-state, charge accumulated in thephotoelectric converter PDC is transferred to the floating diffusionportion FDA, and charge accumulated in the photoelectric converter PDDis transferred to the floating diffusion portion FDB.

Next, at time t6, the control circuit 70 controls the control signalPSW1 from the L level to the H level and then controls the controlsignal PSW1 from the H level to the L level. Thereby, during the periodin which the control signal PSW1 is at the H level, the switch SW1 is inthe on-state, and a signal in accordance with the amount of chargeaccumulated in the photoelectric converter PDC is output from theamplifier transistor M3A to the column amplifier 42 via the output line16A and the switch SW1. Then, the switch SW1 is turned off, and therebyan output signal from the amplifier transistor M3A is held in the columnamplifier 42.

Similarly, at time t6, the control circuit 70 controls the controlsignal PSW2 from the L level to the H level and then controls thecontrol signal PSW2 from the H level to the L level. Thereby, during theperiod in which the control signal PSW2 is at the H level, the switchSW2 is in the on-state, and a signal in accordance with the amount ofcharge accumulated in the photoelectric converter PDD is output from theamplifier transistor M3B to the column amplifier 44 via the output line16B and the switch SW2. Then, the switch SW2 is turned off, and therebyan output signal from the amplifier transistor M3B is held in the columnamplifier 44.

The signals held in the column amplifiers 42 and 44 are then convertedinto digital data, respectively, by an AD converter (not illustrated)arranged on the post-stage.

By driving the imaging device in such a way, it is possible to read outsignals, respectively, independently in accordance with the amount ofcharges accumulated in the four photoelectric converters PDA, PDB, PDC,and PDD. Further, since signals of pixels arranged on the same pixel roware AD-converted at the same time, this simplifies alignment of data ina signal processing unit (not illustrated), and a process of colordevelopment or the like becomes easier.

Next, the driving example when readout of added data is performed fromeach of the unit pixels 12 (second driving example) will be describedwith reference to FIG. 18.

At time t1, the vertical scanning circuit 30 controls the control signalPRES from the L level to the H level and then controls the controlsignal PRES from the H level to the L level. Thereby, during the periodin which the control signal PRES is at the H level, the resettransistors M2A and M2B are in the on-state, and the floating diffusionportions FDA and FDB are reset to the voltage in accordance with thevoltage Vdd.

Next, at time t2, the vertical scanning circuit 30 controls the controlsignals PTXA and PTXC from the L level to the H level and then controlsthe control signals PTXA and PTXC from the H level to the L level.Thereby, during the period in which the control signals PTXA and PTXCare at the H level, the transfer transistors M1A and M1C are in theon-state, and charges accumulated in the photoelectric converters PDAand PDC are transferred to the floating diffusion portion FDA. Further,during the period in which the control signals PTXA and PTXC are at theH level, the transfer transistors M1B and M1D are in the on-state, andcharges accumulated in the photoelectric converters PDB and PDD aretransferred to the floating diffusion portion FDB.

Thereby, a signal in accordance with the total amount of chargesaccumulated in the photoelectric converters PDA and PDC is output to theoutput line 16A. Further, a signal in accordance with the total amountof charges accumulated in the photoelectric converters PDB and PDD isoutput to the output line 16B.

Next, at time t3, the control circuit 70 controls the control signalsPSW1 and PSW3 from the L level to the H level and then controls thecontrol signals PSW1 and PSW3 from the H level to the L level. Thereby,the output line 16A and the output line 16B are connected via the switchSW3, and the signal in accordance with the total amount of chargesaccumulated in the photoelectric converters PDA and PDC and the signalin accordance with the total amount of charges accumulated in thephotoelectric converters PDB and PDD are artificially averaged. Thesignal averaged in such a way is then output to the column amplifier 42via the switch SW1. Then, the switch SW1 is turned off, and thereby theaveraged signal is held in the column amplifier 42.

The signal held in the column amplifier 42 is then converted intodigital data by an AD converter (not illustrated) arranged on thepost-stage.

By driving the imaging device in such a way, it is possible to averageand read out pixel addition data in accordance with the total amount ofcharges accumulated in the photoelectric converters PDA and PDC andpixel addition data in accordance with the total amount of chargesaccumulated in the photoelectric converters PDB and PDD. Thereby,capturing can be performed at up to half the brightness compared to thecase where no pixel addition is performed, and preferable colorreproducibility can be obtained.

As described above, according to the present embodiment, it is possibleto improve sensitivity without deteriorating color reproducibility andacquire an image with a high S/N ratio.

Sixth Embodiment

An imaging system according to a sixth embodiment of the presentdisclosure will be described with reference to FIG. 19. FIG. 19 is ablock diagram illustrating a general configuration of the imaging systemaccording to the present embodiment.

The imaging device 100 described in the above first to fifth embodimentscan be applied to various imaging systems. An example of applicableimaging systems may be a digital still camera, a digital camcorder, asurveillance camera, a copying machine, a fax machine, a mobile phone,an on-vehicle camera, an observation satellite, or the like. Further, acamera module including an optical system such as a lens and an imagingdevice is also included in the imaging system. FIG. 19 illustrates ablock diagram of a digital still camera as an example out of theseexamples.

An imaging system 200 illustrated as an example in FIG. 19 includes animaging device 201, a lens 202 that captures an optical image of anobject onto the imaging device 201, an aperture 204 for changing a lightamount passing through the lens 202, and a barrier 206 for protectingthe lens 202. The lens 202 and the aperture 204 form an optical systemthat converges a light onto the imaging device 201. The imaging device201 is the imaging device 100 described in any of the first to fifthembodiments and converts an optical image captured by the lens 202 intoimage data.

The imaging system 200 further includes a signal processing unit 208that performs processing on an output signal output from the imagingdevice 201. The signal processing unit 208 has a digital signalprocessing unit and performs operations to perform various correction orcompression on the signal output from the imaging device 201 ifnecessary to output image data. When the signal output from the imagingdevice 201 is an analog signal, the signal processing unit 208 mayinclude an analog-to-digital converter circuit on the pre-stage of thedigital signal processing unit. The signal processing unit 208 may beprovided on a semiconductor substrate on which the imaging device 201 isprovided or may be provided on a different semiconductor substrate fromthe semiconductor substrate on which the imaging device 201 is provided.

Further, the imaging system 200 includes a memory unit 210 fortemporarily storing image data therein and an external interface unit(external I/F unit) 212 for communicating with an external computer orthe like. The imaging system 200 further includes a storage medium 214such as a semiconductor memory for performing storage or readout ofimaging data and a storage medium control interface unit (storage mediumcontrol I/F unit) 216 for performing storage or readout on the storagemedium 214. Note that the storage medium 214 may be embedded in theimaging system 200 or may be removable.

Further, the imaging system 200 includes a general control/operationunit 218 that performs various calculation and controls the entiredigital still camera and a timing generation unit 220 that outputsvarious timing signals to the imaging device 201 and the signalprocessing unit 208. Here, the timing signal or the like may be inputfrom the outside, and the imaging system 200 may include at least theimaging device 201 and the signal processing unit 208 that processes anoutput signal output from the imaging device 201.

As described above, according to the present embodiment, the imagingsystem to which the imaging device 100 according to the first to fifthembodiments is applied can be realized.

Seventh Embodiment

An imaging system and a movable object according to a seventh embodimentof the present disclosure will be described with reference to FIG. 20Aand FIG. 20B. FIG. 20A is a diagram illustrating a configuration of theimaging system according to the present embodiment. FIG. 20B is adiagram illustrating a configuration of the movable object according tothe present embodiment.

FIG. 20A illustrates an example of an imaging system related to anon-vehicle camera. An imaging system 300 includes an imaging device 310.The imaging device 310 is the imaging device 100 described in any of theabove first to fifth embodiments. The imaging system 300 includes animage processing unit 312 that performs image processing on a pluralityof image data acquired by the imaging device 310 and a parallaxacquisition unit 314 that calculates a parallax (a phase difference ofparallax images) from the plurality of image data acquired by theimaging system 300. Further, the imaging system 300 includes a distanceacquisition unit 316 that calculates a distance to the object based onthe calculated parallax and a collision determination unit 318 thatdetermines whether or not there is a collision possibility based on thecalculated distance. Here, the parallax acquisition unit 314 and thedistance acquisition unit 316 are an example of a distance informationacquisition device that acquires distance information on the distance tothe object. That is, the distance information is information on aparallax, a defocus amount, a distance to an object, or the like. Thecollision determination unit 318 may use any of the distance informationto determine the collision possibility. The distance informationacquisition device may be implemented by dedicatedly designed hardwareor may be implemented by a software module. Further, the distanceinformation acquisition unit may be implemented by a Field ProgrammableGate Array (FPGA), an Application Specific Integrated Circuit (ASIC), orthe like or may be implemented by a combination thereof.

The imaging system 300 is connected to the vehicle informationacquisition device 320 and can acquire vehicle information such as avehicle speed, a yaw rate, a steering angle, or the like. Further, theimaging system 300 is connected to a control ECU 330, which is a controldevice that outputs a control signal for causing a vehicle to generatebraking force based on a determination result by the collisiondetermination unit 318. Further, the imaging system 300 is alsoconnected to an alert device 340 that issues an alert to the driverbased on a determination result by the collision determination unit 318.For example, when the collision probability is high as the determinationresult of the collision determination unit 318, the control ECU 330performs vehicle control to avoid a collision or reduce damage byapplying a brake, pushing back an accelerator, suppressing engine power,or the like. The alert device 340 alerts a user by sounding an alertsuch as a sound, displaying alert information on a display of a carnavigation system or the like, providing vibration to a seat belt or asteering wheel, or the like.

In the present embodiment, an area around a vehicle, for example, afront area or a rear area is captured by using the imaging system 300.FIG. 20B illustrates the imaging system when a front area of a vehicle(a capturing area 350) is captured. The vehicle information acquisitiondevice 320 transmits an instruction to the imaging system 300 or theimaging device 310. Such a configuration can further improve the rangingaccuracy.

Although the example of control for avoiding a collision to anothervehicle has been described above, the embodiment is applicable toautomatic driving control for following another vehicle, automaticdriving control for not going out of a traffic lane, or the like.Furthermore, the imaging system is not limited to a vehicle such as thesubject vehicle and can be applied to a movable object (movingapparatus) such as a ship, an airplane, or an industrial robot, forexample. In addition, the imaging system can be widely applied to adevice which utilizes object recognition, such as an intelligenttransportation system (ITS), without being limited to movable objects.

Modified Embodiments

The present disclosure is not limited to the embodiments describedabove, and various modifications are possible.

For example, an example in which a part of the configuration of any ofthe embodiments is added to another embodiment or an example in which apart of the configuration of any of the embodiments is replaced with apart of the configuration of another embodiment is also one of theembodiments of the present disclosure.

Further, while the case of the RGBW12 arrangement as the color filterarrangement has been illustrated as one example in the embodimentsdescribed above, the color filter arrangement is not necessarilyrequired to be the RGBW12 arrangement. For example, CMYW arrangementformed of a C pixel having a CF of cyan color, an M pixel having a CF ofmagenta color, a Y pixel having a CF of yellow color, and a W pixel maybe applied as the color filter arrangement.

Further, while a device intended for capturing an image, that is, animaging device has been illustrated as one example in the first to fifthembodiments described above, an application example of the presentdisclosure is not limited to an imaging device. For example, in the caseof application to a device intended for ranging as described in theabove seventh embodiment, it is not always necessary to output an image.In such a case, such a device can be said to be a photoelectricconversion device that converts optical information into a predeterminedelectric signal. An imaging device is one of the photoelectricconversion devices.

Further, the imaging systems illustrated in the above sixth and seventhembodiments are examples of an imaging system to which the photoelectricconversion device of the present disclosure may be applied, and animaging system to which the photoelectric conversion device of thepresent disclosure can be applied is not limited to the configurationillustrated in FIG. 19 and FIG. 20A.

Note that all the embodiments described above are mere embodied examplesin implementing the present disclosure, and the technical scope of thepresent disclosure should not be construed in a limiting sense by theseembodiments. That is, the present disclosure can be implemented invarious forms without departing from the technical concept thereof orthe primary feature thereof.

According to the present disclosure, it is possible to improvesensitivity without deteriorating color reproducibility and acquire animage with a high S/N ratio.

While the present disclosure has been described with reference toexemplary embodiments, it is to be understood that the disclosure is notlimited to the disclosed exemplary embodiments. The scope of thefollowing claims is to be accorded the broadest interpretation so as toencompass all such modifications and equivalent structures andfunctions.

This application claims the benefit of Japanese Patent Application No.2018-246927, filed Dec. 28, 2018, which is hereby incorporated byreference herein in its entirety.

What is claimed is:
 1. An imaging device comprising: a plurality ofpixels each including a photoelectric converter, a holding portion towhich charge generated in the photoelectric converter is transferred,and an output unit that outputs a signal in accordance with an amount ofcharge held in the holding portion; and a control unit that controlsreadout of signals from the plurality of pixels, wherein the pluralityof pixels includes: a plurality of first pixels each configured tooutput a signal in accordance with a light of a first wavelength range,a plurality of second pixels each configured to output a signal inaccordance with a light of a second wavelength range that is differentfrom the first wavelength range, a plurality of third pixels eachconfigured to output a signal in accordance with a light of a thirdwavelength range that is different from the first wavelength range andthe second wavelength range, and a plurality of fourth pixels eachconfigured to output a signal in accordance with a light of a fourthwavelength range that is different from the first wavelength range, thesecond wavelength range, and the third wavelength range, wherein theplurality of pixels forms: a plurality of first unit pixels eachincluding the first pixels and the second pixel but not including thethird pixel, wherein the first pixels and the second pixel share theholding portion, a plurality of second unit pixels each including thefirst pixels and the third pixel but not including the second pixel,wherein the first pixels and the third pixel share the holding portion,a plurality of third unit pixels each including the first pixels and thefourth pixel but not including the second pixel and the third pixel,wherein the first pixels and the fourth pixel share the holding portion,wherein the control unit reads out, from each of the plurality of firstunit pixels, a signal in which signals of the first pixels and a signalof the second pixel are added in the holding portion, wherein thecontrol unit is configured to read out, from each of a part of theplurality of third unit pixels, a signal in which signals of the firstpixels are added in the holding portion by transferring charges of thephotoelectric converters of the first pixels to the holding portionwithout transferring charge of the photoelectric converter of the fourthpixel, and wherein the control unit is further configured to read out,from each of the second unit pixels, a signal in which signals of thefirst pixels and a signal of the third pixel are added in the holdingportion.
 2. The imaging device according to claim 1, wherein the controlunit is further configured to read out, from each of the third unitpixels, a signal in which signals of the first pixels and a signal ofthe fourth pixel are added in the holding portion.
 3. The imaging deviceaccording to claim 1, wherein each of the first unit pixels includesthree of the first pixels and one of the second pixels, wherein each ofthe second unit pixels includes three of the first pixels and one of thethird pixels, and wherein each of the third unit pixels includes threeof the first pixels and one of the fourth pixels.
 4. The imaging deviceaccording to claim 3, wherein four of the pixels forming each of thefirst unit pixels, the second unit pixels, and the third unit pixels arearranged in a matrix of two rows by two columns.
 5. The imaging deviceaccording to claim 1, wherein each of the plurality of second pixels,the plurality of third pixels, and the plurality of fourth pixels issurrounded by the first pixels.
 6. The imaging device according to claim1, wherein the plurality of first pixels are W pixels, the W pixel beinga pixel provided with a white filter.
 7. The imaging device according toclaim 1, wherein the plurality of first pixels are W pixels, the W pixelbeing a pixel provided with a white filter, wherein the plurality ofsecond pixels are R pixels, the R pixel being a pixel provided with ared filter, wherein the plurality of third pixels are B pixels, the Bpixel being a pixel provided with a blue filter, and wherein theplurality of fourth pixels are G pixels, the G pixel being a pixelprovided with a green filter.
 8. The imaging device according to claim7, wherein the plurality of first unit pixels, the plurality of secondunit pixels, and the plurality of third unit pixels are arranged inBayer arrangement in accordance with colors of color pixels included ineach of the unit pixels.
 9. The imaging device according to claim 1,wherein the plurality of first pixels are W pixels, the W pixel being apixel provided with a white filter, wherein the plurality of secondpixels are C pixels, the C pixel being a pixel provided with a cyanfilter, wherein the plurality of third pixels are M pixels, the M pixelbeing a pixel provided with a magenta filter, and wherein the pluralityof fourth pixels are Y pixels, the Y pixel being a pixel provided with ayellow filter.
 10. The imaging device according to claim 1, wherein theholding portion is a floating diffusion portion.
 11. An imaging systemcomprising: the imaging device according to claim 1; and a signalprocessing unit that processes signals output from the pixels of theimaging device.
 12. A movable object comprising: the imaging deviceaccording to claim 1; a distance information acquisition device thatacquires distance information on a distance to an object, from aparallax image based on signals output from the pixels of the imagingdevice; and a control device that controls the movable object based onthe distance information.
 13. An imaging device comprising: a pluralityof pixels each including a photoelectric converter, a holding portion towhich charge generated in the photoelectric converter is transferred,and an output unit that outputs a signal in accordance with an amount ofcharge held in the holding portion; and a control unit that controlsreadout of signals from the plurality of pixels, wherein the pluralityof pixels includes: a plurality of first pixels each configured tooutput a signal in accordance with a light of a first wavelength range,a plurality of second pixels each configured to output a signal inaccordance with a light of a second wavelength range that is differentfrom the first wavelength range, and a plurality of third pixels eachconfigured to output a signal in accordance with a light of a thirdwavelength range that is different from the first wavelength range andthe second wavelength range, wherein the plurality of pixels forms: aplurality of first unit pixels each including the first pixels and thesecond pixel but not including the third pixel, wherein the first pixelsand the second pixel share the holding portion, a plurality of secondunit pixels each including the first pixels and the third pixel but notincluding the second pixel, wherein the first pixel and the third pixelshare the holding portion, and a plurality of fourth unit pixels eachincluding the first pixels but not including the second pixels and thethird pixels, wherein the first pixels share the holding portion, andwherein the control unit is configured to: read out, from each of theplurality of first unit pixels, a signal in which signals of the firstpixels and a signal of the second pixel are added in the holdingportion, and read out, from each of the plurality of second unit pixels,a signal in which signals of the first pixels and a signal of the thirdpixel are added in the holding portion.
 14. The imaging device accordingto claim 13, wherein the control unit is configured to read out, fromeach of the plurality of fourth unit pixels, a signal in which signalsof the plurality of first pixels are added in the holding portion. 15.The imaging device according to claim 13, wherein each of the first unitpixels includes three of the first pixels and one of the second pixels,wherein each of the second unit pixels includes three of the firstpixels and one of the third pixels, and wherein each of the fourth unitpixels includes four of the first pixels.
 16. The imaging deviceaccording to claim 13, wherein the plurality of first pixels are Gpixels, the G pixel being a pixel provided with a green filter, whereinthe plurality of second pixels are R pixels, the R pixel being a pixelprovided with a red filter, and wherein the plurality of third pixelsare B pixels, the B pixel being a pixel provided with a blue filter. 17.A signal processing device comprising a signal processing unit thatprocesses signals output from an imaging device including a plurality ofpixels including a first pixel having higher sensitivity than a secondto fourth pixels, the second pixel configured to output a signalincluding color information of a first color, the third pixel configuredto output a signal including color information of a second color that isdifferent from the first color, and the fourth pixel configured tooutput a signal including color information of a third color that isdifferent from the first color and the second color, wherein the imagingdevice outputs first addition data in which a signal of the second pixeland a signal of the first pixel are added, second addition data in whicha signal of the third pixel and a signal of the first pixel are added,third addition data in which a signal of the fourth pixel and a signalof the first pixel are added, and fourth addition data in which signalsof the first pixel are added, and wherein the signal processing unitcalculates color data of the first color by subtracting the fourthaddition data from the first addition data, calculates color data of thesecond color by subtracting the fourth addition data from the secondaddition data, and calculates color data of the third color bysubtracting the fourth addition data from the third addition data. 18.The signal processing device according to claim 17, wherein the firstpixel is a W pixel, the W pixel being a pixel provided with a whitefilter, wherein the second pixel is a R pixel, the R pixel being a pixelprovided with a red filter, wherein the third pixel is a B pixel, the Bpixel being a pixel provided with a blue filter and wherein the fourthpixel is a G pixel, the G pixel being a pixel provided with a greenfilter.